Apparatus and method of oscillating a flex-vane type agitator

ABSTRACT

A VERTICAL AXIS WASHING MACHINE INCLUDING A TUB, A SELECTIVELY ROTABLE BASKET IN THE TUB, AND A ROTATIONALLY OSCILLATABLE AGITATOR WITHIN THE BASKET AND INCLUDING VANES OF A FLEXIBLE MATERIALHAVING A RELATIVELY LOW LODULUS OF ELASTICITY. DRIVE MEANS PROVIDES SHORT STROKES, HIGHFREQUENCY OSCILLATION OF THE AGITATOR.

sept. 28, 1971 J, RHUBBARD Em. 3,608,110

APPARATUS AND METHOD OF OSCILLATING A FLEX-VANE TYPE AGITATOR Filed March 9, 1970 Hail u ii i w K w rma/r: uc" ,rr/eax: me l mem/f ,mc

(A) v f5) /C' u' z un y'. u1-manual I l l J United States Patent O APPARATUS AND METHOD F OSCILLATING A FLEX-VANE TYPE AGITATOR James R. Hubbard, Moorestown, NJ., and Elmer C.

Vanderslice and John B. Reid, Philadelphia, Pa., assignors to Philco-Ford Corporation, Philadelphia, Pa.

Filed Mar. 9, 1970, Ser. No. 17,598

Int. Cl. D06f 17/08 U.S. Cl. 8-159 10 Claims ABSTRACT 0F THE DISCLOSURE A vertical axis washing machine including a tub, a selectively rotatable basket in the tub, and a rotationally oscillatable agitator within the basket and including vanes of a exible material having a relatively low modulus of elasticity. Drive means provides short strokes, highfrequency oscillation of the agitator.

BACKGROUND OF THE INVENTION This invention relates to vertical axis laundry apparatus, and more particularly to an improved method of and machine for washing clothes.

Vertical axis washing machines of well-known type utilize rotationally oscillatable agitators which describe arcs of from about 160 to `210 and operate at frequencies of from about 100 to 60 cycles per minute. Efforts directed to simplication of the agitator drive system have resulted in other known types of machines employing, variously: vertical pulsating action of an agitator partly of an elastomeric material; eccentric action of an agitator of a rigid plastic material; and wobble-plate action of an agitator partly of an elastomeric material. 'Ihese other known types of washing machines have exhibited considerable tendency to tangle clothes. A solution to clothes tangling has been to lower the frequency of agitation. However this remedy, disadvantageously, is accompanied by a reduced washing action when compared with the rotationally oscillatable agitator.

It is an objective of the present invention to provide an improved method of and machine for washing clothes by the use of an unusually short stroke and high frequency oscillating, flexible agitator, to achieve the combined advantages of both of the above described general classes of machines.

SUMMARY OF THE INVENTION `In achievement of the foregoing as well as other objectives, the invention is applicable to that type of washing machine employing a rotationally oscillatable agitator having a stroke varying from zero velocity at one end to zero velocity at the opposite end, with an oscillating stroke velocity that is substantially sinusoidal. In accordance with the invention, the preferred range of stroke arc is from a minimum of yabout 65 to a maximum of about 105, with a corresponding frequency range from about 250 c.p.m. to 155 c.p.m. Combinations of arc and frequency in such optimum ranges provide an approximate average of from about 520 to about 550 degrees of agitator rotation per second.

The manner in which the foregoing as well as other objectives and advantages of the invention may best be achieved will be more fully understood from a consideration of the following description, taken in light of the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. l is a perspective View of laundry apparatus of a type embodying the invention, and with parts broken away or removed for convenience of illustration; and

g 3,608,110 Patented Sept. 28, 1971 FIGS. 2, 3 and 4 are diagrammatic representations of operational features of apparatus seen in FIG. 1, and illustrating method aspects of the invention.

DESCRIPTION OF PREFERRED EMBODIMENT With more particular reference to the drawing, and :first to FIG. 1, a washing machine 10 of the vertical axis type includes a generally cylindrical open top` tub 11 and a rotatable, perforate basket 12 disposed therein. Under one condition of operation, the basket and agitator may be rotated at a relatively high rate of speed to centrifuge wash-fluid from the clothes. Under another condition of operation, the basket may be held stationary while agitator 13 is oscillated, rotationally, in achievement of either a washing or a rinsing action. Mechanism for spinning the basket and agitator, and for operating the agitator while preventing rotation of the basket, includes a suitable transmission 15- and a drive motor 14 connected thereto by a pulley and belt assembly 16. Mechanism of the above-described type is well known in the art, and detailed description thereof is not necessary for an understanding of the invention. However, it will be appreciated that the transmission differs from the usual prior art apparatus in that agitator oscillationproducing elements thereof are of such relative proportions as to afford the improved agitator stroke frequency and arc to be described in detail in what follows. Linkage which can be proportioned to achieve the purposes of the invention may, for example, be of the type disclosed in U.S. Pat. No. 2,836,993 of Harold D. Johnson et al., issued June 3, 1958, and assigned to the assignee of the present invention.

Agitator 13 is of that general type disclosed and claimed in U.S. Pat. No. 3,464,239 of James R. Hubbard and John B. `Reid, issued lSept. 2, 1969, and assigned to the assignee of the present invention. More specifically, agitator 13 includes a central post portion 17 provided with an upper set of three vertically extending radial vanes 21 preferably spaced 12.0 apart, and a lower set of vertically extending radial vanes 22 also spaced 120 apart, and offset when viewed in plan, substantially 60 relative to the upper vanes.

The upper vanes 21 are of lesser radius than the lower vanes 22, and corresponding upper and lower vanes are interconnected by helical vane sections 23 of lesser radial extension than either of vanes 21 and 22. A downwardly aring skirt 24 is provided at the lower end of post 17 and affords partial support of vane 22. Each of the lower vanes 22 is undercut with respect to the skirt to such an extent that substantial portions of these vanesare free to ilex about transverse axes thereof. For reasons to be more fully explained in what follows, agitator 13 is molded from polypropylene.

In further special accordance with the invention, transmission 15 is operable by drive motor 14 through pulley and belt assembly 16 to oscillate agitator 13 through a rotational arc in the range from about 6'5 to about 105. The aforementioned drive means further is operable to produce these oscillations at a frequency in the range from about 250 cycles per minute to about cycles per minute.

Using the relationship:

Average stroke velocity 2X (Stroke are, degrees) X (Frequency, s.p.m.) 60

there is achieved. an average agitator velocity of approximately 540 per second, and a preferred minimum of at least 500 per second.

In operation of the above described apparatus, basket 12 is filled with clothes followed by introduction of wash fluid into the basket, in accordance with known practice, and until tub 11 is filled substantially to a level corresponding approximately to the level of the upper vanes 21 of lesser radial extension. Extensive testing has shown that operation of the agitator in accordance with the above described parameters achieves an advantageous clothes and wash fluid motion characterized by toroidal movement of a rotating annular mass of clothes and fluid, wherein the surface of the wash fluid is relatively active. In tests of the apparatus, the combined clothes and uid activity advantageously has resulted in remarkably consistent degrees of soil removal and clothes action for various clothes loading conditions. Moreover, and surprisingly, the above described apparatus has been found to achieve its highly effective action with little or no tangling of clothes.

In arriving at the invention above described, in both its apparatus and method aspects, tests were conducted on a vertical axis washing machine provided with an agitator 13 disposed within a cylindrical basket 12 having a height of about 15 inches and a diameter of about 181%@ inches, and using a maximum water lill height of about 131/16 inches and a minimum fill height of about 10T/16 inches.

In further accordance with the invention, agitator velocity vs. stroke arc relationships were investigated, and with reference to FIG. 2, a set of three curves A, B, and C evolved to illustrate preferred rotationally oscillating agitator stroke velocities (/sec.) vs. stroke arc relationships. As seen from these curves, for a rotationally oscillating agitator the velocity will vary from zero at one end of the stroke to zero velocity at the other end of the stroke, with generally sinusoidal intermediate values as indicated by the several curves.

Criteria for washability were then established, based on rate of clothes turnover as a measure of soil removal uniformity, with a given clothes load. In correlating operating parameters to turnover rate, and with reference to FIG. 4, mathematical expressions were developed for best it curves of the several operating parameters of the inventive apparatus and method. More specifically, there are shown relationships comprising clothes turnovers per minute (Y) vs. AHAM load size in lbs. ('L),

'stroke arc in degrees (A), and frequency in strokes per minute X100 (F). Also, and with reference to FIG. 3, agitator materials were investigated, and, using the relationship clothes turnover per minute (Y) vs. agitator material modulus of elasticity-p.s.i., as the criteria, those materials having a modulus of elasticity in the range from about 150,000 to about 200,000 p.s.i. were found to exhibit optimum clothes turnover rates. Acceptable clothes turnover rates were obtained in the range from about 125,000 to about 300,000 p.s.i. It should be noted that to either side of the line of peak performance, the turnover rate tended to decrease rather sharply.

Data for the `curve based on load size (L) was obtained using an agitator stroke arc of 87 at an operating frequency of 177 strokes per minute (s.p.m.),'wherea's the curve based on agitator stroke arc (A) evolved from data obtained for both 5.4 1b. and 8 lb. clothes loads, also at an operating frequency of 177 s.p.m. Data for the curves based on frequency (F) was obtained using both 5.4 lb. land 8 lb. clothes loads at an agitator stroke arc of 87. Utilizing computer techniques to combine the data illus trated graphicaly, yielded the following expression for turnover (Y) in terms of strokel arc (A), stroke frequency (F), and load size (L) Summarizing, optimum turnover (Y) has been achieved for stroke arc (A) in the range from about 65 to about 105, at a frequency in the range from about 250 cycles per minute to about 155 cycles per minute, for a given clothes load (L), and in a medium wherein a cxible agitator was used.

The turnover rate (Y) hasbeen found to be representative of the degree of soil removal uniformity, and is used in the determination of the above described parameters. Hence when considering the several interrelationships contemplated by the invention, the term Y is synonymous with soil removal uniformity with a given clothes load.

Thus for a given range of load sizes (L) (as determined by physical sizes of the tub and basket, usually dictated by size of the cabinet structure), and for a desired turnover rate (Y), an agitator stroke and frequency range can be determined for a flexible agitator of the type disclosed.

We claim:

1. In a laundry machine of the vertical axis, oscillating agitator type, the improvement which consists in: providing motor driven agitator drive means effective to oscillate said agitator through an arc in the range from a minimum of about 65 to a maximum of about 105, said drive means being effective to produce such oscillations at a frequency in the range from a maximum of about 250 cycles per minute to a minimum of about cycles per minute.

further characterized in that said drive means drives said agitator at an average velocity of approximately 540 degrees per second.

3. A laundry machine in accordance with claim 1, and further characterized in that said agitator is of the ilexvane type.

4. A laundry machine in accordance with claim 3 in which said agitator is of the flexevane type having a modulus of elasticity in the range from about 125,000 p.s.i. to about 300,000 p.s.i.

5. A method of washing clothes, using a vertical axis oscillating agitator, comprising: oscillating said agitator through an arc in the range from a minimum of about 65 to a maximum of about 105; and producing such oscillations at a frequency in the range from a maximum of about 250 cycles per minute to a minimum of about 155 cycles per minute.

6. A method in accordance with claim `5, and further characterized in that the arc and frequency of oscillation are such that twice the product of the arc times the frequency, divided by 60, yields an average agitator drive velocity in the region of from about 500 per second to about 550 per second.

7. A method according to claim 5, and further characterized in that said agitator is of the flex-Vane type.

8. A method according to claim 7, and further characterized in that at least the vanes of said agitator are of a material having a modulus of elasticity in the range from about 125,000 p.s.i. to about 300,000 p.s.i.

9. A method of washing clothes, using a vertical axis oscillating agitator, comprising: oscillating said agitator through a stroke arc and at a stroke frequency such that twice the product of the arc times the frequency, divided by 60, yields an average agitator drive velocity of at least 500 degrees per second.

10. A method according to claim 9, and further characterized in that said arc and frequency are so chosen that the average agitator drive velocity does not exceed about 550 degrees per second.

References Cited UNITED STATES PATENTS 2,383,783 8/1945 Dunham 68-133X 3,117,434 1/1964 Byrd et al 68--134 3,381,504 5/1968 Smith 68--134X WILLIAM I. PRICE, Primary Examiner U.S. Cl. X.R. 

